fab-root@fab-ux-predator:~
$ cat /sys/class/backlight/*/max_brightness
11
fab-root@fab-ux-predator:~
$ echo 10 | sudo tee /sys/class/backlight/*/max_brightness
tee: /sys/class/backlight/acpi_video0/max_brightness: Permission denied
10
fab-root@fab-ux-predator:~
$ ll /sys/class/backlight/*/max_brightness
-r--r--r-- 1 root root 4.0K Jun 29 20:56 /sys/class/backlight/acpi_video0/max_brightness
fab-root@fab-ux-predator:~
$ sudo chmod a+rw /sys/class/backlight/acpi_video0/max_brightness
fab-root@fab-ux-predator:~